Battery pack—cordless power device interface system

ABSTRACT

A battery pack for a cordless power tool and a cordless power tool and battery pack combination includes the battery pack having a retention member that pivotally engages a retention member of the power tool and a latch system in which one of the battery pack and power tool has a ball and the other of the power tool and battery pack has a latch that engages the ball. Spring biased actuators may be used to open the latch to enable insertion or release of the ball from the latch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/558,176 filed Mar. 31, 2004. The disclosure of the above applicationis incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to cordless power devices that use batterypacks, and more particularly, an interface system in a cordless powerdevice and battery pack that interfaces the two together.

BACKGROUND OF THE INVENTION

Some cordless power devices have an integrated battery pack that rarelyneeds to be removed by the user. The battery pack remains in the devicefor both charge and discharge cycles. Cell phones are a typical exampleand have battery packs that are charged while installed in the phones.This is possible for two main reasons: the battery can usually providesufficient power for the cell phone for a relatively long period of timesuch as one to two days, and the user is not severely inconvenienced bycharging the battery while it is still in the phone. Cell phones when onare typically in the stand-by mode waiting for the user to engage in acall and are typically used in the call mode where the user is engagedin a phone call for only short periods of time. Since cell phones drawrelatively little power when in the stand-by mode, the battery cantypically provide sufficient power to power the cell phone for the oneto two day period.

These reasons do not apply to other types of cordless power devices,such as power tools. These other types of cordless power devices areoften used continuously or frequently for relatively long period oftimes, such as during a work shift, and may use more than one batterypack during that period. For example, a cordless saw or drill used on aconstruction site may be used throughout the work shift and may usemultiple battery packs during the shift. Plugging such a cordless powertool into a charger during use would be inconvenient, obviating theadvantages provided by a cordless power tool, and in some cases isn'tpossible due to the lack of AC mains power where the cordless power toolis being used. For these reasons, cordless power devices such ascordless power tools are not well suited for using integral batteries.These cordless power devices, particularly cordless power tools forprofessional use, therefore have removable battery packs so that usedbattery packs can be swapped with fresh battery packs during the workshift and the used battery packs placed in a charger for recharging.

The design of the interface system between the battery pack and thecordless power device is important. “Interface system” as used hereinmeans the elements of the cordless power device and battery pack thatcooperate when the battery is inserted and removed in the cordless powerdevice, including the elements that releasably secure the battery packin the cordless power tool and those that provide the electricalconnection(s) between the battery pack, the cordless power device, andthe charger.

The designs of interface systems presently used for cordless powerdevices that use battery packs, particularly cordless power tools, leavesomething to be desired with regard to ease of use, latching, and/orelectrical connections. The two most common types of interface systemsused in cordless power tools having battery packs are the “tower cell”design, which is used in the DEWALT® 7.2V–18V systems, and the“rail-style” design, which is used in the DEWALT® 24V system.

U.S. Pat. No. 4,871,629 issued Oct. 3, 1989 for “Latching Arrangementfor Battery Packs” shows an example of a cordless power tool in whichthe “tower-cell” design interface system is used. A distinguishingcharacteristic of the “tower-cell” interface system is that theremovable battery pack includes a tower extending from a main body orbase in which at least one battery cell is typically disposed, with theremaining battery cells disposed in the main body. The “tower-cell”interface system has a number of advantages. They include ease ofinsertion and removal. The tower aligns the battery terminals to thetool to facilitate insertion. One handed insertion is both possible andconvenient. The latch buttons are placed in a natural grip position,making them easy to actuate with one hand, and gravity aids in theremoval of the battery pack. The advantages of the “tower-cell”interface system also include utilization of the dead space in the toolhandle in that the “tower-cell” fills up space in the foot of the tool,making the overall battery pack size when it is inserted in the toolseem smaller and user familiarity in that the “tower-cell” interfacesystem is a commonly used interface system in today's cordless powertools.

The “tower-cell” design interface system can have certain disadvantages.They include the possibility of thermal imbalance due to the“tower-cell” being separated from the larger cluster of cells in themain body of the battery pack and thus tends to be at a differenttemperature during operation of the tool. The “tower-cell” design alsotypically introduces extra manufacturing processes and components, thusincreasing manufacturing complexity. In a number of products utilizingthe “tower-cell” interface system the “tower-cell” connections in thebattery pack have presented reliability concerns. The relatively smallterminal block area of the “tower-cell” design tends to preclude addingadditional terminals to the terminal block. Also, the entire weight ofthe battery pack is supported by the latches which secure the batterypack to the tool and the contact area of the latches to the tool tendsto be small, placing a relatively high amount of stress on the latches.

U.S. Pat. No. 6,057,608 issued May 2, 2000 for a “Cordless Power ToolSystem” shows an example of a cordless power tool in which the“rail-style” design interface system is used. A distinguishingcharacteristic of the “rail-style” design is that the battery packhousing has rails that ride on rails or rail sections of the toolhousing. The “rail-style” design interface system has a number ofadvantages. They include battery pack retention in that there areseparate mechanisms for supporting the weight of the battery pack (e.g.,rails) and securing the battery pack to the tool (e.g., latch). Therelatively large terminal block area of the battery pack facilitatessystem expansion in that there is space to add additional terminals. Thecells are all contained in the body of the battery pack and no one cellis located remote from the other cells so that there is better thermalbalance among the respective cells. The “rail-style” design interfacesystem has better manufacturing consistency than the “tower-cell” designinterface system in that there is no need to deal with the additionalmanufacturing complexity added by needing to deal with the “tower-cell.”Since all the cells are connected in the same way, the “rail-style”design interface system does not have the reliability concerns due tothe “tower-cell” connections that some products using the “tower-cell”design interface system have experienced.

The “rail-style” design interface system can have certain disadvantages.They include rail contamination which makes insertion and removal of thebattery pack more difficult. Insertion and removal of the battery packis awkward compared to the “tower-cell” design interface system in thattwo hands are typically required to insert or remove the battery pack.Also, pushing or pulling on the battery pack during insertion andremoval creates a moment about the tool making it more difficult to holdthe tool in place. The battery pack housing has a “clamshell”construction and the tolerances of the rail dimensions are difficult tohold in the assembly of the clamshell, making rail travel “sticky.” Thefoot of the tool has dead space in that there is no “tower-cell” thatfills the space in the foot of the tool.

SUMMARY OF THE INVENTION

A battery pack for a cordless power tool and a battery pack and cordlesspower tool combination. Each of the power tool and battery pack has atleast one retention member that pivotally engages the retention memberof the other of the power tool and battery pack. It also includes alatch system where one of the power tool and the battery pack has a balland the other of the power tool and battery pack has a latch thatengages the ball. In an aspect of the invention, the power tool has theball and the battery pack has the latch.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1A is a side cross-sectional view of a cordless power tool andbattery pack interface system in accordance with an embodiment of theinvention;

FIG. 1B is a top view of the battery pack of FIG. 1A;

FIG. 1C is a schematic view of the terminal blocks of FIGS. 1A and 1B asthey are mated together;

FIG. 1D is a cross-sectional view of the terminal blocks of theinterface system of FIGS. 1A and 1B having a spring-loaded ejector pin;

FIG. 2A is a top view of the battery pack of FIGS. 1A and 1B with avariation of the latch;

FIG. 2B is a cross-sectional view of the battery pack of FIG. 2A takenalong the line 2B—2B of FIG. 2A.

FIG. 3A is a side cross-sectional view of the battery pack of FIGS. 1Aand 1B with a variation of the latch;

FIG. 3B is a top cross-sectional view of the battery pack of FIG. 3A;

FIG. 4A is a side cross-sectional view of an interface system for acordless power tool and battery pack in accordance with an embodiment ofthe invention having a “trailer hitch” type of latching system;

FIG. 4B is a rear cross-sectional view of the interface system of FIG.4A;

FIG. 4C is a top cross-sectional view of the interface system of FIG.4A;

FIG. 4D is cross-sectional view taken along the line 4D—4D of FIG. 4C;

FIGS. 5A–5B are views of an alternative “trailer-hitch” type latchsystem of FIGS. 4A–4D;

FIGS. 5C–5D are views of a second alternate “trailer-hitch” type latchsystems of FIGS. 4A–4D;

FIG. 6A is a bottom view of a cordless power tool having an alternativeterminal block in accordance with an aspect of the invention;

FIG. 6B is a top view of a battery pack having an alternative terminalblock in accordance with an aspect of the invention;

FIG. 7A is a bottom view of an alternative terminal block in accordancewith an aspect of the invention;

FIG. 7B is a front view of the terminal block of FIG. 7A;

FIG. 7C is a top view of a terminal block that mates with the terminalblock of FIG. 7A;

FIG. 7D is a side view of the terminal block of FIG. 7C;

FIG. 7E is a cross sectional view taken along the line 7E—7E of FIG. 7A;

FIG. 8A is a side perspective view of an interface system for a cordlesspower tool and battery pack having a modular interface section inaccordance with an aspect of the invention;

FIG. 8B is a top view of the battery pack of FIG. 8A; and

FIG. 8C is a cross-sectional view taken along the line 8C—8C of FIG. 8B;

FIG. 9A is a schematic system diagram of the functional control of abattery pack and battery charger;

FIG. 9B is a schematic system diagram of the functional control of abattery pack and tool according to an aspect of the invention;

FIG. 9C is a flow chart showing regulation of the motor voltage of thecordless power tool of FIG. 9B;

FIG. 10 is a side view of a cordless power tool having a floatingterminal block according to an aspect of the invention;

FIG. 11A is a top view of a variation of the cordless power tool andbattery pack interface system interface system of FIGS. 1A and 1B;

FIG. 11B is a side view of the battery pack of the cordless power tooland battery pack interface system of FIG. 11A; and

FIG. 11C is a cross-section view of the cordless power tool and batterypack interface system of FIG. 11A taken along the line 11C—11C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses. For convenience, the invention will bediscussed in the context of cordless power tools but it should beunderstood that it can be used in any cordless power device wherebattery packs are used.

FIGS. 1A and 1B show an interface system 100 in accordance with anembodiment of the invention in a cordless power tool 102 and a removablebattery pack 104. As used herein, “interface system” means the elementsof the cordless power tool and the battery pack that are used in matingthe cordless power tool and battery pack and securing the battery packin the cordless power tool.

Interface system 100 includes a rear retention member 112(illustratively an outwardly extending lip or flange) at a rear end 110of a foot 108 of a housing 106 of cordless power tool 102. Interfacesystem 100 also includes a front retention member 114 (illustratively aninwardly extending lip or flange) at a front 116 of foot 108 of toolhousing 106. Interface system 100 also includes terminal block 118mounted within foot 108 of tool housing. Terminal block 118 includespower terminals 120 and may also include one or more keys 122. It mayalso include one or more data terminals 124. Power terminals 120 areillustratively heavier duty terminals compared with data terminals 124and are used to carry power between battery pack 104 and cordless powertool 102. In the embodiment shown in FIGS. 1A and 1B, there areillustratively two power terminals 120 for the positive side and twopower terminals 120 for the negative or common side. Power terminals 120are coupled to a motor (not shown) of cordless power tool 102. Thepositive and negative power terminals 120 may be coupled directly to themotor, such as would be the case when a controller 126 of battery pack104 provides power control for cordless power tool 102, or one or bothof positive and negative power terminals 120 may be coupled through acontroller and/or a switch (not shown) of cordless power tool 102 inconventional fashion. In an embodiment, one or both of positive andnegative power terminals 120 may be coupled to the motor through aswitch of cordless power tool 102 even with controller 126 providingpower control for cordless power tool 102. In this embodiment, theswitch of cordless power tool 102 may for example switch cordless powertool 102 on and off and provide a signal to controller 126 of batterypack 104 that controller 126 uses in, for example, providing variablespeed control of cordless power tool 102.

While the use of one or more keys 122 is preferred for the reasonsdiscussed below, it should be understood that key(s) 122 could bedispensed with. Similarly, data terminals 124 may be dispensed with ifthere is no data communication between battery pack 104 and cordlesspower tool 102. Similarly power connections could be accomplished usingone positive and one negative power terminal 120.

Interface system 100 includes battery pack 104 having a rear retentionmember 128 illustratively located at an upper rear 130 of battery pack104, at least one latch 132 illustratively located at a front 134 ofbattery pack 104, and a terminal block 136. Terminal block 136 includespower terminals 138 and may also include data terminals 140 andkeyway(s) 142. When battery pack 104 is attached to cordless power tool102, power terminals 138 of terminal block 136 of battery pack 104 matewith power terminals 120 of terminal block 118 of cordless power tool102, data terminals 140 of terminal block 136 mate with data terminals124 of terminal block 118 and key(s) 122 of terminal block 118 mate withkeyway(s) 142 of terminal block 136. Power terminals 120 and dataterminals 124 of terminal block 118 are illustratively male terminalswith power terminals 138 and data terminals 140 of terminal block 136illustratively being female terminals. Using female terminals interminal block 136 of battery pack 104 provides better isolation of theterminals from possible contact with conductive surfaces when thebattery pack is not received in cordless power tool 102, or in acharger. It should be understood, however, that power terminals 120could be female terminals with power terminals 138 then being maleterminals and that data terminals 124 could be female terminals withdata terminals 140 being male terminals. In this regard, some of powerterminals 120 could be male and the remainder of power terminals 120 befemale, with power terminals 138 then being the opposite. The same couldbe the case with data terminals 124 and 140, some could be male with theremainder being female and data terminals 140 then being the opposite.Along these lines, terminal block 136 could have key(s) 122 withterminal block 118 then having keyway(s) 142. Also, terminal block 118could have one or more key(s) 122 and one or more keyway(s) 142, withterminal block 136 then having corresponding keyway(s) 142 and key(s)122.

In the embodiment of FIGS. 1A and 1B, retention member 128illustratively includes an inwardly projecting flange or lip 144 thatextends at least partially across battery pack 104. Retention member 128may illustratively be formed as an integral part of upper rear 130 ofbattery pack 104 or may be a separate member, such as a dowel pin, thatis affixed to upper rear 130 of battery pack 104.

In the embodiment of FIGS. 1A and 1B, latch 132 includes a hook member146. Hook member 146 may illustratively include a vertical (as orientedin FIG. 1A) member 148 extending at least partially across battery pack104 having a flange or lip 150 at an upper end 152. A lower end 154 ofvertical member 148 is pivotally mounted to battery pack 104. Latch 132further includes an actuator member 156 that extends from verticalmember 148 out the front of battery pack 104. Actuator member 156illustratively extends from a 149 of vertical member 148 that is betweenlower end 154 of vertical member 148 and upper end 152 of verticalmember 148. A spring 158 is disposed in battery pack 104 to urge latch136 to the latched position. In the embodiment shown in FIGS. 1A and 1B,spring 158 extends between terminal block 136 and a side 160 of verticalmember 148 of hook member 146 that is opposite a side 162 of verticalmember 148 from which actuator member 156 extends.

Battery pack 104 also includes battery cells 164 as is conventional.Battery pack 104 may also include controller 126 and fan 166.

Interface system 100 interfaces cordless power tool 102 and battery pack104 together as follows. When battery pack 104 is mated with cordlesspower tool 102, rear lip 112 at the rear end 110 of foot 108 of toolhousing 106 is placed under lip 144 of retention member 128 at the upperrear 130 of battery pack 104. Retention member 128 and rear lip 112 ofrear end 110 of foot 108 of tool housing 106 provide a pivot 113 (FIG.1C) about which battery pack 104 and cordless power tool 102 rotate withrespect to each other. Battery pack 104 is then rotated upwardly (asoriented in FIG. 1A) until latch 132 engages front lip 114 at the frontof foot 108 of tool housing 106. In the embodiment shown in FIGS. 1A and1B, lip 150 of hook member 146 of latch 132 engages inwardly projectingfront lip 114 of tool housing 106. Hook member 146 compresses spring 158as lip 150 of hook member 146 passes over front lip 114. Spring 158urges hook member 146 toward front lip 114 maintaining lip 150 of hookmember 146 engaged with front lip 114 of tool housing 106. Rear lip 112of tool housing 106 engaging retention member 128 of battery pack 104and latch 132 of battery pack 104 engaging front lip 114 of tool housing106 retain battery pack 104 in cordless power tool 102.

Power terminals 120, key(s) 122 and data terminals 124 of terminal block118 of cordless power tool 102 may illustratively be staggered as shownin FIGS. 1C. As battery pack 104 is pivoted up into cordless power tool102, key(s) 122 engage the respective keyway(s) 142 of terminal block136 of battery pack 104 first to align terminal block 118 and terminalblock 136. Power terminals 120, since they are typically larger, morerobust terminals than data terminals 124, next engage power terminals138 of terminal block 136, further aligning terminal block 118 andterminal block 136. Data terminals 124 of terminal block 118 then engagedata terminals 140 of terminal block 136.

It should be understood that key(s) 122 and keyway(s) 142 could bedispensed with and the alignment function achieved by the staggeredrelationship between power terminals 120 and data terminals 124. Whenbattery pack 104 is pivoted into cordless power tool 102, powerterminals 120 of terminal block 118 would first engage power terminals138 of terminal block 136, with data terminals 124 of terminal block 118subsequently engaging data terminals 140 of terminal block 136. Theengagement of the more robust power terminals 120 in terminal block 118to power terminals 138 in terminal block 136 aligns terminals blocks118, 136 before data terminals 124 of terminal block 118 engage dataterminals 140 of terminal block 136, helping prevent any damage to theless robust data terminals 124 due to terminal blocks 118, 136 beingmisaligned when data terminals 124 of terminal block 118 engage dataterminals 140 of terminal block 136.

In an aspect of the invention, key(s) 122 may illustratively be springloaded or a separate spring loaded ejector pin(s) 170 provided in one ofterminal blocks 118, 136 with a corresponding receptacle 172 in theother terminal block 118, 136, as shown in FIG. 1D. The spring loadedkey(s) 122 or spring loaded ejector pin 170 would urge the terminalblocks 118, 136 apart when latch 132 is released, aiding the ejectionand removal of battery pack 104 from cordless power tool 102. The springaided ejection would make ejection of battery pack 104 more consistenteven should interface system 100 become contaminated, such as with dirtor other contaminants. The cooperation of spring loaded ejector pin 170and receptacle 172 would align terminal blocks 118, 136 during insertionof battery pack 104 into cordless power tool 102 in the same manner asdiscussed above. It should be understood that each of terminal blocks118 and 136 could have one or more spring loaded ejector pin 170 withthe other terminal block 118, 136 having corresponding receptacles 172.It should also be understood that spring loaded ejector pin(s) 170 couldbe used without a corresponding receptacle 172 in the other terminalblock 118, 136 if the alignment function provided by spring loadedejector pin(s) 170 engaging receptacle(s) 172 isn't needed, or thisalignment function is provided by key(s) 122 and keyway(s) 142. Itshould also be understood that the body 176 of the terminal block 118and/or the body 178 of the terminal block 136 could be spring loaded toprovide the same eject function without spring loaded ejector pins orkeys.

In an aspect of the invention, the female power and data terminals,which are illustratively power terminals 138 and data terminals 140 ofterminal block 136 have open sides 174, 176, respectively, opposite thesides in which the male power terminals 120 and data terminals 124 areinserted. These open sides allow debris and other contaminants thatmight get in the female terminals to fall or be pushed out.

In an aspect of the invention, by having the male and female power anddata terminals in terminal blocks 118 and 136 received in slots thatclosely conform to them, the terminals are supported so thatcommercially available crimp-on terminals may illustratively be used.For example, an AMP brand terminal 794974 available from TycoElectronics (AMP) of Harrisburg, Pa. could be used for the male powerterminals, an AMP brand terminal 61626-1 used for the female powerterminals, an AMP brand terminal 350654-1 used for the male dataterminals and an AMP brand terminal 30536-1 used for the female dataterminals.

In the embodiment shown in FIGS. 1A and 1B, one latch 132 andcorresponding front lip 114 of tool housing 106 are used which arecentered in battery pack 104 (when viewed from the top as best seen inFIG. 1B). It should be understood that a plurality of latches 132 andcorresponding front lips 114 could be used. For example, if two latches132 were used, they would illustratively be located on either side ofbattery pack 104 (again as viewed from the top). Front lip 114 may thenbe a single lip 114 that extends across the battery pack or two lips 114disposed in tool housing 106 opposite the respective hook members 146 ofthe two latches 132. While the embodiment shown in FIGS. 1A and 1B hasbeen described with latch 132 at the front of the battery pack 104 andretention member 128 at the rear, it should be understood that latch 132could be at the rear of battery pack 104 and the retention member 128 atthe front. In this case, the lips that may be rear and front retentionmembers 112, 114 of tool housing 106 would similarly be located at thefront and rear of tool housing 106, respectively.

Terminal blocks 118, 136 may illustratively be disposed in cordlesspower tool 102 and battery pack 104 so that terminal block 136 isbetween the pivot point 113 where rear retention member 112 of toolhousing 106 pivots about retention member 128 of battery pack 104 andlatch area 133 defined by front retention member 114 and latch 132, andpreferably as close as possible to this latch area 133. Having theterminal blocks as close as possible to the latch area 133 minimizesmisalignment. Also, the further the terminal blocks are from the pivotpoint 113, the straighter the path that the terminal blocks will takewith respect to each other when battery pack 104 is inserted intocordless power tool 102. This could be facilitated by placing terminalblocks forward of the latches to further move them from the pivot point.Terminal blocks 118, 136 may illustratively be made of electricallynon-conductive plastic.

In an aspect of the invention as can best be seen in FIG. 1C, whenkey(s) and keyway(s) 142 are provided in the terminal blocks, such askey(s) 122 in terminal block 118 and keyway(s) 142 in terminal block136, the key(s) and keyway(s) are positioned so that they are closet tothe pivot point 113. This helps ensure that the key(s) and keyway(s)mate first. The data terminals would illustratively be furthest awayfrom the pivot point 113, helping ensure that they mate last, with thepower terminals between the key(s)/keyway(s) and the data terminals.

FIGS. 2A and 2B show a variation of interface system 100 shown in FIGS.1A and 1B. Common elements will be identified with the same referencenumerals and the discussion will focus on the differences. In theinterface system shown in FIGS. 2A and 2B, latches 132 are disposed sothat they extend out the sides 202, 204 of battery pack 104, atgenerally the front of battery pack 104, as opposed to out the front 134of battery pack 104. Corresponding retention members 114 (such as lips)are then disposed on sides of tool housing 106 generally at the front oftool housing 106 and actuator members 156 project out through sides 202,204 of battery pack 104. Disposing latches in battery pack 104 so thatactuator members 156 in particular project out the sides of battery pack104 puts actuator members 156 in a more natural grip position as well asdistributing the weight of the battery pack 104 on the latches 132 moreevenly.

FIGS. 3A and 3B show a latch 300 that is an alternative to latch 132.Common elements will be identified with the same reference numerals andthe discussion will focus on the differences. Latch 300 includes hookmember 302 having a vertical (as oriented in FIG. 3A) member 304 and ahorizontal member 306. Vertical member 304 includes outwardly extendinglip 150 at upper end 152. Horizontal member 306 has a trapezoidal shapewhen viewed from above as shown in FIG. 3B with tapered sides 324. Aspring 305 is disposed in battery pack 104 so as to contact verticalmember 304 and urge hook member 302 toward its latched position wherelip 150 engages front retention member 114 of tool housing 106 (FIG.1A). Latch 300 also includes actuator members 308 disposed in recesses309 in opposed sides 310, 312 of battery pack 104. Each actuator member308 includes a shaft 314 having a tapered distal end 316 and a button318 at an end 320 of shaft 314 opposite tapered distal end 316. A spring322 is disposed around each shaft 314 between button 318 and therespective side 310, 312 of battery pack 104 to urge actuator members308 outwardly away from horizontal member 306 of hook member 302 oflatch 300.

In operation, as discussed, spring 305 urges hook member 302 of latch300 to the latched position. To unlatch latch 300, buttons 318 ofactuator members 308 are depressed. Tapered distal ends 316 of shaft 314of actuator members 308 contact the tapered sides 324 of the trapezoidalshaped horizontal member 306, urging horizontal member 306 toward therear 130 of battery pack 104, thus moving lip 150 out of engagement withretention member 114 of tool housing 106 (FIG. 1A). Placing actuatormembers 308 in the sides 310, 312 of battery pack 104 positions them ina more natural grip position, as discussed above with respect to theinterface system shown in FIGS. 2A and 2B.

FIGS. 4A–4D show an alternate interface system 400. Elements that arecommon with the elements of interface system 100 shown in FIGS. 1A and1B will be identified with the same reference numerals and thediscussion will focus on the differences.

Interface system 400 utilizes a “trailer hitch” style of latch system401. Latch system 401 includes a ball 404 that extends from a bottom 402of foot 108 of tool housing 106 of cordless power tool 102 generally atfront 116 of tool housing 106. Ball 404 may illustratively be disposedat the end of a shaft 406 that extends from bottom 402 of foot 108 oftool housing 106. Latch system 401 also includes a latch 416 disposed inbattery pack 104 to capture ball 404 when battery pack 104 is placed incordless power tool 102. Latch 416 may illustratively include an outersleeve 418 that extends laterally across at least a portion of batterypack 104 from side 202 and an inner sleeve 420 that extends laterallyacross at least a portion of battery pack 104 from opposite side 204 ofbattery pack 104. A distal portion 422 of inner sleeve 420 is receivedin a distal portion 424 of outer sleeve 418. Distal portion 422 of innersleeve 420 includes a distal end member 426 that extends transverselyacross inner sleeve 420 and distal portion 424 of outer sleeve 418includes a distal end member 428 that extends transversely across outersleeve 418. Outer sleeve 418 includes an actuator member 430 extendingoutwardly through side 202 of battery pack 104 from a proximal end 432of outer sleeve 418. Inner sleeve 420 includes an actuator member 434extending outwardly through side 204 of battery pack 104 from a proximalend 436 of inner sleeve 420. Springs 438 are disposed between a distalend 440 of distal end member 428 of outer sleeve 418 and side 204 ofbattery pack 104. Springs 438 are also disposed between a distal end 442of distal end member 426 of inner sleeve 420 and side 202 of batterypack 104. Proximal ends 444, 446 of distal end members 426, 428 of innerand outer sleeves 420, 418 may illustratively include recesses 448, 450at generally their centers that conform to shaft 406. Springs 438 urgethe distal end members 426, 428 of inner and outer sleeves 420, 418together so as to capture shaft 406 therebetween, latching battery pack104 in cordless power tool 102. Pressing actuator members 430, 434forces distal end members 428, 426 of outer and inner sleeves 418, 420apart so that battery pack 104 can be removed from cordless power tool102.

In the embodiment shown in FIGS. 4A–4D, rear retention member 112 at therear 110 of foot 108 of tool housing 106 may illustratively be replacedby two retention members 408. Each retention member 408 mayillustratively be a hook member that extends downwardly and outwardlyfrom bottom 402 of foot 108 of tool housing 106. The hook member mayillustratively have a generally vertical member 410 that extendsgenerally downwardly (as oriented in FIGS. 4A and 4B) from bottom 402 offoot 108 of tool housing 106 and an outwardly extending lip 412 at adistal end 414.

Retention member 128 of battery pack 104 is illustratively replaced by arod 452, such as a steel dowel, that extends transversely across batterypack 104 through at least one upwardly opening recess 454 in a top 455of battery pack 104. Recess 454 may illustratively extend across batterypack 104 to permit both retention members 408 to be received therein, orbattery pack 104 have a recess 454 for each retention member 408.

When battery pack 104 is inserted into cordless power tool 102,retention members 408 are first inserted in recess(s) 454 in the top 455of battery pack 104 so that lips 412 of retention members 408 areinserted under rod 452. Battery pack 104 and cordless power tool 102 arethen rotated together. Actuator members 430, 434 are pressed, openinglatch 416 so that ball 404 can pass through latch 416. Actuator members430, 434 are then released and latch 416 captures shaft 406 to securebattery pack 104 and cordless power tool 102 together. It should beunderstood that top edges 456, 458 of proximal ends 444, 446,respectively, of distal end members 426, 428 of inner and outer sleeves420, 418 can be beveled about recesses 448, 450 to allow the latch 416to be opened by ball 404 as it passes through recesses 448, 450.

Referring to FIGS. 5A–5D, a variation 500 of latch 416 is shown. Commonelements will be identified with the same reference numerals and thediscussion will focus on the differences. In latch 500, one or moresprings 438 are disposed between distal end 442 of distal end member 426of inner sleeve 420 and an inwardly facing surface 502 of proximal end432 of outer sleeve 418. Alternatively or additionally, one or moresprings 438 are disposed between distal end 440 of distal end member 428of outer sleeve 418 and an inwardly facing surface 504 of proximal end446 of inner sleeve 420.

While the foregoing trailer hitch style latch system has been describedwith cordless power tool 102 having ball 404 and battery pack 104 havinglatch 416, it should be understood that cordless power tool 102 can havethe latch and battery pack 104 can have the ball.

FIGS. 6A–6B show a variation of terminal blocks 118, 136 of theembodiments of FIGS. 1A–1D. Common elements will be identified with thesame reference numerals and the discussion will focus on thedifferences. FIG. 6A is a bottom view of cordless power tool 102 andFIG. 6B is a top view of battery pack 104. Cordless power tool 102includes terminal block 600 and battery pack 104 includes correspondingterminal block 602. It should be understood, however, that terminalblock 600 could be disposed in battery pack 104 with terminal block 602disposed in cordless power tool 102. Terminal blocks 600, 602 mayillustratively be made of electrically non-conductive plastic.

Terminal block 600 includes power terminals 604 and may illustrativelyinclude key(s) 606 and data terminals 608. Power terminals 604 andkey(s) 606 illustratively extend laterally from one side 610 of terminalblock 600 and data terminals 608 extend laterally from an opposite side612 of terminal block 600.

Terminal block 602 illustratively includes first receptacle block 614and second receptacle block 616 in spaced relation to first receptacleblock 614 defining a recess 617 therebetween. First receptacle block 614includes power terminals 618 and keyway(s) 620 corresponding to powerterminals 604 and key(s) 606 of terminal block 602. Second receptacleblock 616 includes data terminals 622 corresponding to data terminals608 of terminal block 600.

When battery pack 104 and cordless power tool 102 are rotated together,terminal block 600 is received in recess 617 between first and secondreceptacle blocks 614, 616 of terminal block 602 of battery pack 104.Terminal block 600 and first and second receptacle blocks 614, 616 ofterminal block 602 may illustratively be dimensioned so that terminalblock 600 is received between first and second receptacle blocks 614,616 before any of the key(s) or terminals of terminal block 600 begin tomate with the keyway(s) and terminals of terminal block 602 to alignterminal block 600 and terminal block 602. Key(s) 606 (if present) ofterminal block 600 mating with keyway(s) 620 of terminal block 602assist in aligning terminal blocks 600, 602, preferably before powerterminals 604 and data terminals 608 of terminal block 600 mate withrespective power terminals 618 and data terminals 622 of terminal block602. Power terminals 604 of terminal block 600 next mate with powerterminals 618 of terminal block 602 to further align terminal block 600and terminal block 602 before data terminals 608 of terminal block 600begin mating with data terminals 622 of terminal block 602. In thisregard, key(s) 606, power terminals 604 and data terminals 608 ofterminal block 600 may be staggered, with key(s) 606 being the furthestfrom the bottom of cordless power tool 102 and data terminals 608 beingthe closest. Also, terminal blocks 600, 602 may illustratively bedisposed so that side 610 of terminal block 600 and first receptacleblock 614 of terminal block 602 are closest to the pivot point such aspivot point 113 and second side 612 of terminal block 600 and secondreceptacle block 616 of terminal block 602 are furthest away.

FIGS. 7A–7E show another variation for terminal blocks 118 and 136 ofFIGS. 1A and 1B. In terminal block 700, the terminals and key(s) (ifkey(s) are provided), designated generally by reference numeral 702,have opposed ends secured in opposed block sections 704, 706 of terminalblock 700 that are in spaced relation so that the terminals and keysbridge a gap or recess 708 defined by opposed block sections 704, 706.Terminal block 700 may illustratively be a U-shaped block with a bightsection 710 extending between opposed block sections 704, 706. Opposedblock sections 704, 706 and bight section 710 may illustratively be madeof electrically non-conductive plastic.

A corresponding terminal block 720, shown in FIGS. 7C and 7D has a blockshaped body 722 having receptacles 724 for receiving terminals anddefining keyway(s), defined generally by reference numeral 726. Terminalblock 700 may illustratively be disposed in cordless power tool 102 andterminal block 720 disposed in battery pack 104. Alternatively, terminalblock 700 may be disposed in battery pack 104 and terminal block 720disposed in cordless power tool 102. Terminal blocks 700, 720 mayillustratively be made of electrically non-conductive plastic. Terminalsand key(s) may illustratively be staggered in terminal block 700 (asshown in FIG. 7E) with the key(s) being furthest from bight section 710and the data terminals being closest, with terminal block 720 beingformed so that as terminal blocks 700, 720 are mated together, thekey(s) of terminal block 700 first mate with the keyway(s) of terminalblock 720, the power terminals of terminal blocks 700, 720 next matewith the data terminals of the terminals blocks 700, 720 being the lastto mate. This facilitates alignment of terminal blocks 700, 720 beforethe power terminals mate, the mating of the power terminals furtherfacilitating alignment of the terminal blocks 700, 720 before the dataterminals mate.

FIGS. 8A–8C show an interface system 800 that is a variation ofinterface systems 100 and 400. Common elements will be identified withthe same reference numerals and the discussion will focus on thedifferences. One principal difference is that interface system 800 usesa modular approach where a modular interface section 802 on the batterypack 104 remains the same for different battery voltages and styles.This modular interface section 802 is then mated with different batterycups 804 to provide a consistent interface and footprint with thevarious cordless power tools with which it is used, such as cordlesspower tool 102.

Using the modular interface approach provided by modular interfacesection 802 across all cordless power tools and batteryvoltages/configurations would likely significantly reduce tooling costsas the same parts would be used for the modular interface section 802regardless of the battery voltage/configuration of the battery cup 804.Any voltage/configuration of battery cup 804 could be attached tomodular interface section 802 and have a pre-designed interfaceconnection to the tool(s). This flexibility to use anyvoltage/configuration of battery cup 804 with modular interface section802 provides for the use of various types of cell chemistries in variousform factors.

By having all cordless power tools and battery packs in all cordlesspower tool product lines use the same modular interface approach, suchas using modular interface section 802 with all the battery packs,cordless power tools could be built that could accept any voltage orbattery cell chemistry, with the voltage then being regulated to theappropriate level. The cordless power tool and/or battery pack wouldthen illustratively include electronics to regulate the voltage of themotor used in the cordless power tool. This would allow cordless powertool users to “mix and match” any of the battery packs having modularinterface section 802 with any of the cordless power tools configured tointerface with modular interface section 802. The user would thus havethe ability to optimize combinations of cordless power tools and batterypacks for their preferred run time, power, weight, etc.

This is described in greater detail with reference to FIGS. 9A–9C. FIG.9A shows a battery pack 104 (which illustratively has modular interfacesection 802) coupled to a charger 900. The plurality of battery cells164 are interconnected to provide the desired voltage and current. Thepower connections for charging and discharging the battery pack 104 arethrough terminals A and B. Inside the battery pack 104 there is a packID component 912 which, when used with the charger 900 or cordless powertool 102 (FIG. 9B), can define the chemistry of battery cells 164,capacity of battery pack 104, and/or other characteristics to either thecharger's electronic control unit 913 or the cordless power tool 102electronic control unit 914 (FIG. 1B). Battery pack 104 may also haveone or more temperature sensors (such as a thermistor) 915 connected toboth the charger unit via terminal F and an electronic control unit 917inside the battery pack 104. The electronic control unit 917 mayillustratively be responsible for the protection of the cells 164 forany condition exposed on the terminals A, B by the user (charger, tool,and/or user tampering). The discharge or charge current can be clampedor discontinued by the use of semi-conductor devices Q1 and Q2, whichare illustratively MOSFETs. The electronic control unit 917 mayillustratively be powered by a separate power supply, such as internalpower supply 918. A driver circuit 919 may illustratively be disposedbetween electronic control unit 917 and control inputs of semi-conductordevices Q1, Q2.

When connected to a charger 900, the charger electronic control unit 913can be powered from the battery pack 104's power supply 918 throughterminals A and C. This is only exemplary as other means for poweringthe charger electronic control unit 913 can be employed. Battery andcharger information can be exchanged via data terminals D and E. Thecharger electronic control unit 913 then will drive power controller 920of charger 900 to deliver the desired voltage and current to the batterypack 104. It should be understood that terminals A–F may illustrativelybe appropriate power terminals 138 and data terminals 140 of terminalblock 136 of battery pack 104 and corresponding power and data terminalsof a terminal block (not shown) of charger 900.

With reference to FIG. 9B, the battery pack 104 is shown connected to acordless power tool 102, which may illustratively be a smart tool havingan electronic control unit 914. Electronic control unit 914 can bepowered from the battery pack 104 power supply 918 through terminals Aand C. The cordless power tool 102 may contain a switch S1 that pullsterminal B high when the semi-conductor Q1 is off. If semi-conductor Q1is left off while the battery pack 104 is dormant, and suddenly theswitch S1 is pulled, terminal B could be used to wake the battery pack104 from a dormant mode of operation. The tool electronic control unit914 could be configured to read the trigger switch 921 position andreport that data back to the battery pack 104 electronic control unit917 through data terminals D and E. The battery pack 104 electroniccontrol unit 917 will vary the PWM duty cycle of the power supplied tomotor 908 of cordless power tool 102 through semi-conductor Q1 to powermotor 908 at a desired motor speed. While semi-conductor Q1 is off, thediode D1 in cordless power tool 102 will re-circulate any inductivemotor current to prevent voltage spikes. It should be understood thatsemi-conductor Q1 could alternatively be included in the cordless powertool 102 and controlled by tool electronic control unit 914 to vary thePWM duty cycle.

FIG. 9C is a flow chart showing the regulation of the voltage of motor908 of cordless power tool 102. At step 950, battery pack 104 electroniccontrol unit 917 obtains information about the rated voltage of themotor 908, such as by querying tool electronic control unit 914 forinformation about the rated voltage of the motor. This information istransmitted by tool electronic control unit 914 and received by batterypack electronic control unit 917 at step 952. It should be understoodthat the particular manner that the rated voltage of the motor isobtained by battery pack electronic control 917 is not important. Otherways in which battery pack electronic control unit 917 could obtain thisinformation include reading a code, such as a resistance, in cordlesspower tool 102 where the code is indicative of the rated voltage of themotor 908.

At step 954, battery pack electronic control unit 917 determines acoefficient K that is the ratio of the rated voltage of the motor 908 tothe rated voltage of battery pack 104. In a variation, the coefficient Kis the ratio of the rated voltage of the motor 908 to the actual voltageof battery pack 104. At step 956, battery pack electronic control unit917 obtains the position of trigger switch 921 from cordless power tool102, such as from tool electronic control unit 914, which is shown inthe FIG. 9C as a percentage of how closed the trigger switch 921 is. Itshould be understood that the particular manner that battery packelectronic control unit 917 obtains the information about the positionof trigger switch 921 is not important. For example, the trigger switch921 may have a potentiometer (as is conventional) and the wiper of thispotentiometer coupled to battery pack electronic control unit 917through terminals of terminal blocks 118, 136 (FIG. 1) which batterypack electronic control unit 917 would then use to determine theposition of trigger switch 921.

At step 958, battery pack electronic control unit 917 outputs the PWMcontrol signal to semi-conductor Q1 having a duty cycle determined bymultiplying the coefficient K by the trigger switch position percentage.As can be seen, if the trigger switch is fully closed (having a positionpercentage of 100%) the duty cycle of the PWM control signal will be thecoefficient K.

It should be understood that above steps could be implemented in toolelectronic control unit 914 with tool electronic control unit 914 thendriving Q1, such as might be the case if Q1 was provided in cordlesspower tool 102 instead of in battery pack 104. Tool electronic controlunit 914 and battery pack electronic control unit 917 may illustrativelybe microcontrollers programmed to implement the above steps. But itshould be understood that tool electronic control unit 914 and batterypack electronic control unit 917 can be any control device capable ofimplementing the above steps, such as, by way of example and not oflimitation, application specific integrated circuits, discrete digitallogic, and discrete analog circuits. Further, an alternative tool nothaving an electronic control unit 914 (not shown) may just have thetrigger switch 921 configured as a potentiometer and coupled to batterypack 104 via appropriate terminals in the terminal blocks 118, 136(FIG. 1) of cordless power tool 102 and battery pack 104. The batterypack electronic control unit 917 would then control the semi-conductorQ1 to switch at the desired duty cycle to create the intended motorspeed based on the position of the trigger switch 921 and thecoefficient K. The battery pack electronic control unit 917 would thenobtain the information about the rated voltage of motor 908 of cordlesspower tool 102 by reading a code in cordless power tool 102 as discussedabove.

Taking a motor 908 having a rated voltage of 24V and battery pack 104having a rated voltage of 48V as examples, the coefficient K would be50% or 0.5. When trigger switch 921 is fully closed (having a positionpercentage of 100%), the duty cycle of the PWM control signal would be50% of 100%, or 50%, which would be the maximum duty cycle of the PWMcontrol signal. A 50% duty cycle of the PWM control signal results inthe voltage of battery pack 104 being applied to motor 908 50% of thetime, resulting in an effective voltage of 24V being applied to motor908 to run motor 908 at full speed. If the trigger switch 921 is halfclosed, its position percentage would be 50% resulting in a PWM controlsignal having a 25% duty cycle, with the voltage of battery pack 104then being applied to motor 908 25% of the time to run motor 908 at halfspeed.

In an aspect of the invention, modular interface section 802 mayillustratively include first and second clamshell sections 806, 808. Theclamshell sections 806, 808 are mated together to form modular interfacesection 802. The clamshell arrangement permits rod 452 to be easilyassembled in modular interface section 802 during production. A sleeve810 is provided in each clamshell section 806, 808. One end of rod 452is inserted into one of sleeves 810 and the clamshell sections 806, 808then brought together with the other end of rod 452 being inserted intothe other sleeve 810 as this occurs.

In an aspect of the invention, clamshell sections 806, 808 mayillustratively have recesses 812 disposed therein in which a terminalblock such as terminal block 136 is received. Terminal block 136 mayillustratively be loosely captured in recesses 812 providing a floatingterminal block. Also, terminal block 118 may illustratively be looselymounted in cordless power tool 102 providing a floating terminal block,as shown in FIG. 10.

In an aspect of the invention, terminal block 136 may illustrativelyhave an upwardly (as oriented in FIG. 8C) opening tapered recess 814disposed therein that mates with a corresponding tapered projection 816that extends from the bottom 402 of the foot 108 of tool housing 106.When battery pack 104 is inserted into cordless power tool 102, taperedprojection 816 engages tapered recess 814 before terminal blocks 118,136 engage, aligning terminal blocks 118, 136 before their respectiveterminals begin to mate.

FIGS. 11A–11C show a variation 1100 of the interface system 100 of FIGS.1A, 1B, 2A and 2B. Like elements are identified with the same referencenumbers and only the differences are discussed. Battery pack 104includes a front retention member 1102, illustratively a lip or flange,under which front retention member 114 of tool housing 106 is received.Latches 132 are disposed in the sides of battery pack 104, such as shownin FIGS. 2A and 2B, but at the upper rear of sides 202, 204 of batterypack 104 as opposed to the front of sides 202, 204. Battery pack 104 isheld to cordless power tool 102 by front retention member 114 of toolhousing 106 mating with front retention member 1102 of battery pack 104and by latches 132. Rear retention member 112 of tool housing 106 andrear retention member 128 of battery pack 104 (FIG. 1A) can thus bedispensed with.

The above described inventions each provide one or more of the followingadvantages. Ease of insertion of the battery pack 104 is comparable tothat of the “tower-cell” type of battery pack. The battery pack can beinserted in the cordless power tool with one hand. The latch buttons oractuator members can be located in a natural grip position. Gravityand/or a spring loaded ejector pin aid in removal of the battery pack.

Retention of the battery pack in the cordless power tool is enhanced.The weight bearing elements have more surface area. Separate latchelements and weight bearing elements isolate to a great extent the latchfrom the weight bearing elements.

Better thermal balance than the “tower-cell” type battery pack isprovided. There is no “tower-cell” and the modular interface approachallows for the use of different battery cup designs.

Reliability and manufacturing are enhanced. Since there is notower-cell, the reliability issues presented by the tower-cellconnections are eliminated. The latch system is more robust. A clamshellhaving mating sections can be used to provide a modular interfacesection that can be affixed to various different types of battery cups.The modular interface approach reduces tooling requirements. The matingclamshell sections provide for easy assembly of the pivot rod that isused as a retention member in the battery pack. Tolerances of theclamshell sections can be looser since rails are no longer needed.

System expansion is enhanced in that there is available space to enlargethe terminal blocks.

The modular interface approach allows the use of the same interfaceacross all cordless products, battery cell types and battery voltages. Asmart tool could accept any battery pack using the modular interfacesection or a smart battery could be mated to any tool.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A cordless power tool and battery pack combination, comprising: a.each of the power tool and battery pack having at least one retentionmember that pivotally engages the retention member of the other of thepower tool and battery pack; and b. a latch system including one of thepower tool and the battery pack having a ball and the other of the powertool and battery pack having a latch that captures the ball betweenmovable portions of the latch.
 2. The apparatus of claim 1 wherein thepower tool has the ball and the battery pack has the latch.
 3. Theapparatus of claim 2 wherein the ball extends toward the battery packfrom a bottom of a foot of the power tool.
 4. The apparatus of claim 2wherein the power tool's retention member includes at least one hookextending toward the battery pack and the battery pack's retentionmember includes at least one rod extending transversely across at leasta portion of the battery pack.
 5. The apparatus of claim 1 wherein thelatch includes inner and outer sleeves that extend laterally across atleast a portion of the one of the battery pack and power tool thatincludes the latch, each sleeve including a recess therein, a portion ofthe inner sleeve slidably received in a portion of the outer sleeve, thelatch including at least one spring that urges the sleeves together tocapture the ball between the sleeves in the recesses of the sleeves. 6.The apparatus of claim 5 wherein the ball includes a shaft and the shaftis captured in the recesses of the sleeves.
 7. The apparatus of claim 5wherein the latch includes at least one spring for each sleeve urgingthe recess in that sleeve toward the recess in the other sleeve.
 8. Theapparatus of claim 7 wherein each sleeve has an actuator member coupledto it, the actuator members, when pressed, moving the sleeves withrespect to each other to open the latch.
 9. The apparatus of claim 1wherein the retention members are at generally a rear of the power tooland battery pack and the latch system is at generally a front of thepower tool and battery pack.
 10. A cordless power tool and battery packcombination, comprising: a. each of the power tool and battery packhaving at least one retention member that pivotally engages theretention member of the other of the power tool and battery pack; and b.a latch system including the power tool having a ball extending from abottom of a foot of the power tool and the battery pack having a latchthat engages the ball, the latch including inner and outer sleeves thatextend laterally across at least a portion of the battery pack, eachsleeve including a recess therein, a portion of the inner sleeveslidably received in a portion of the outer sleeve, the latch includingat least one spring for each sleeve, the springs urging the sleevestogether so that the ball is captured between the recesses of thesleeves.
 11. The apparatus of claim 10 wherein the ball includes a shaftand the shaft is captured in the recesses of the sleeve.
 12. Theapparatus of claim 10 wherein the retention members are at generally arear of the power tool and battery pack and the latch system is atgenerally a front of the power tool and battery pack.
 13. A battery packfor a power tool having a retention member and a ball, comprising: a. atleast one retention member that pivotally engages the retention memberof the power tool; and b. a latch for capturing the ball of the powertool between movable portions of the latch.
 14. The apparatus of claim13 wherein the latch includes inner and outer sleeves that extendlaterally across at least a portion of the battery pack, each sleeveincluding a recess therein, a portion of the inner sleeve slidablyreceived in a portion of the outer sleeve, the latch including at leastone spring for each sleeve, the springs urging the sleeves together sothat the ball is captured between the recesses of the sleeves.
 15. Theapparatus of claim 14 wherein the retention member of the battery packis at generally a rear of the battery pack and the latch is atgenerally, a front of the battery pack.